Convert Celsius to Fahrenheit, Kelvin, and Rankine. Visual thermometer, comfort zone indicator, conversion formulas, and reference temperature table.
Celsius (°C) is the world's most widely used temperature scale, standard in science, medicine, and daily life across most countries. Named after Swedish astronomer Anders Celsius, the scale is defined by two reference points: water freezes at 0 °C and boils at 100 °C at standard atmospheric pressure.
This comprehensive converter handles all four major temperature scales: Celsius, Fahrenheit, Kelvin, and Rankine. Enter a temperature in any scale and instantly see equivalents in all others, plus a visual thermometer showing where the value falls on the spectrum from absolute zero to extreme heat. The comfort zone indicator provides an instant human-relevant assessment of the temperature.
Whether you are converting weather forecasts between metric and imperial, working with scientific data in Kelvin, calibrating industrial equipment using Rankine, or simply checking cooking temperatures, this tool provides instant, accurate conversion with all the formulas and reference values you need. Check the example with realistic values before reporting.
Celsius is the default temperature scale in most countries and in much of science, but people often still need Fahrenheit, Kelvin, or Rankine equivalents. This page keeps those scales together so weather, cooking, lab, and engineering readings can be compared in one place. It is a practical bridge when one source is metric and the next instrument, recipe, or report is not.
°C to °F: °F = °C × 9/5 + 32 °F to °C: °C = (°F − 32) × 5/9 °C to K: K = °C + 273.15 K to °C: °C = K − 273.15 °C to °R: °R = (°C + 273.15) × 9/5
Result: 212 °F, 373.15 K, 671.67 °R
100 °C is the boiling point of water at standard pressure. Using the formula: 100 × 9/5 + 32 = 212 °F. For Kelvin: 100 + 273.15 = 373.15 K. For Rankine: 373.15 × 9/5 = 671.67 °R.
Anders Celsius proposed his scale in 1742, originally with 0 as the boiling point and 100 as the freezing point. After his death, the scale was inverted to its modern form by Carolus Linnaeus. In 1948, the 9th General Conference on Weights and Measures officially renamed the "centigrade" scale to "Celsius" to honor its creator.
Scientific literature almost exclusively uses Celsius (or Kelvin for thermodynamics). Medical thermometers worldwide use Celsius, with fever thresholds at 38°C (mild), 39°C (moderate), and 40°C+ (high). Lab equipment, chemical reactions, and pharmaceutical storage all reference Celsius.
The hottest natural temperature recorded on Earth is 56.7°C (134°F) at Death Valley in 1913. The coldest is -89.2°C (-128.6°F) at Vostok Station, Antarctica in 1983. The cosmic microwave background radiation has a temperature of 2.725 K (-270.425°C).
Multiply by 9/5 (or 1.8) and add 32. Formula: °F = °C × 9/5 + 32. Example: 25°C × 1.8 + 32 = 77°F.
The US, Belize, the Cayman Islands, Palau, and a few other territories use Fahrenheit due to historical convention. The rest of the world adopted Celsius as part of the metric system.
Both use the same degree size, but Kelvin starts at absolute zero (0 K = -273.15°C). To convert: K = °C + 273.15. Kelvin is used in science because it eliminates negative temperatures for thermodynamic calculations.
Rankine uses the same degree size as Fahrenheit but starts at absolute zero (0°R = -459.67°F). It is used primarily in some US engineering applications, particularly in thermodynamics.
No single temperature equals the same number in all four scales. However, -40 is equal in Celsius and Fahrenheit (-40°C = -40°F). All scales agree that absolute zero is the minimum.
Room temperature is approximately 20-22°C = 68-72°F = 293-295 K = 528-531°R. The exact value depends on the building and the context, but that range is the usual everyday reference.